Method of making metal bonded abrasives by electroless deposition

ABSTRACT

The invention provides a process of making an abrasive article whereby abrasive particles or a mixture of abrasive particles and filler particles are secured to a form by a layer of adhesive and the layer of adhesive is dissolved prior to securing the abrasive particles or the mixture of abrasive particles and filler particles to the form by a metallic bond. This is achieved by packing the form tightly in a container with packing particles prior to dissolving the adhesive.

United States Patent Keeleric 1 Oct. 2, 1973 METHOD OF MAKING METAL BONDED 2,367,286 1/1945 Kceleric 51/309 ABRASVES ELECTROLESS 538223; llliii i fii li 21533; n onyc a, DEPOSITION 2,904,4l8 9/1959 Fahnoe .i 5 U293 [76} Inventor: George Friis Keeleric, 35 Ballybane 3,343,932 9/1967 Juillcrat 51/293 Rd., Merview, Galway, County Galway, Ireland Primary Examiner-Donald J. Arnold 221 Filed: May 7, 1971 Pyle [2]] Appl. No.: 141,185 [57] ABSTRACT The invention provides a process of making an abrasive [52] l 3 2 gg article whereby abrasive particles or a mixture of abrag fi C c 4 3 g sive particles and filler particles are secured to a form 1 0 can I by a layer of adhesive and the layer of adhesive is dis solved prior to securing the abrasive particles or the mixture of abrasive particles and filler particles to the [56] Reta-wees C'ted form by a metallic bond. This is achieved by packing UNITED STATES PATENTS the form tightly in a container with packing particles 2,571,772 10/1951 Simons 5l/309 prior to dissolving the adhesive. 2,342,l2l 2/1944 Ciell 5l/308 3,310,390 3/1967 Nehru et al... 51 309 7 Claims, 5 Drawing Figures 2,785,060 3/1957 Keeleric 5l/309 ff f4 METHOD OF MAKING METAL BONDED ABRASIVES BY ELECTROLESS DEPOSITION This invention relates to a method of securing particles onto a surface and in particular to the construction of wear resistant and/or abrasive surfaces.

In the manufacture of abrasive tools and wear resistant surfaces of the type which comprise a blank or body, on the working surfaces of which abrasive parti- It is also known to apply diamond particlesdirectly to the surface of a tool or other article. According to this process the tool is placed in a porous container which is filled with small diamond particles. The container is placed in an electroplating bath, which contains an anode, the tool body is electrically connected up as a cathode, electrical direct current is applied and some metal is deposited onto the tool body to secure a number of diamond particles to it. Thetool may then be removed from the porous container and additional bonding material may be applied by conventional electroplating. Unfortunately, there are certain disadvantages in using this method of making an abrasive tool or wear resistant surface. Firstly, the porous container must be packed with diamond particles each time the process is performed; a considerable number of these diamond particles are accordingly inactive thus increasing the inventory of costly diamond particles held. Secondly, in electroplating a greater concentration of metal is usually deposited on points and sharp corners thus making it difficult and costly to deposit an even layer of bonding metal onto an irregular shaped tool body or abrasive surface. Thirdly, the diamond particles so secured to the tool body or abrasive surface are usually closely packed together thus resulting in what is very often undesirable spacing of the cutting points of the diamond particles.

The method of making abrasive tools have been described in many Specifications for example;

U.S. Pat. Nos. 2,359,920, 2,367,286, 2,368,473 and 2,785,060 all in the name of George F. Keeleric. The methods of the plating with nickel by chemical reduction, of metallic surfaces, or as it is often referred to the electroless deposition of nickel are well known and are described in U.S. Pat. Nos. 2,532,283 (Brenner Chase and Riddell) and 2,929,742 (Minjer and Brenner).

The present invention is directed towards providing a construction of and a process of making an abrasive article which will overcome the aforesaid disadvantages.

Principal features of the present invention are the use of an adhesive for securing the abrasive particles to a form and its subsequent removal prior to depositing a metallic bond around the layer of particles on the form and the use of chemical reduction for the depositing of the metallic bond.

The invention willbe more clearly understood from the following description of a preferred embodiment thereof given by way of example only with reference to the accompanying drawings in which:

FIG. 1 is a front view of a diamond file manufactured according to the invention,

FIG. 2 is a cross-sectional view along the lines I] II of FIG. I,

FIG. 3 is a cross-sectional view similar to FIG. 2 of the diamond file in the process of manufacture,

FIG. 4 is an enlarged front view of portion of the diamond file during the process of manufacture, and

FIG. 5 is a partially diagrammatic view of an apparatus suitable for carrying out the invention.

Referring to the drawings and initially to FIGS. 1 and 2 there is illustrated a diamond file of triangular crosssection having a shank l and a working portion 2. The

file comprises a form or file blank 3, on portion of which abrasive particles such as diamond particles 4 are secured by a layer of nickel 5 deposited by chemical reduction to form the working portion 2. The diamond particles 4 are distributed over the working surface with a controlled coverage as will be explained hereinafter. It will be noted that the fileblank 3 is chamfered at its edges 6 to avoid any sharp comers in the file. The chamfered edges 6 are of substantially the same dimensions as the diamond particles 4.

Referring to FIG. 5 there is illustrated apparatus for the plating of electroless or chemical reduction. The

apparatus comprises a plating bath 10, connected by means of pipes 11 and a heat exchanger 12 to a supply tank 13; the supply tank 13 is connected by means of pipes 11 and a pump 14 to a drain off tank 15 which is in turn connected by pipes 11 to the plating bath 10. The plating bath is divided by means of a filter disc 16 into an upper compartment 17 and a lower compartment 18. The upper compartment 57 is supplied with a gas exhaust pipe 19. The plating solution used can be for example be as laid out in US. Pat. No. 2,929,742 (Minjer and Brenner) namely an aqueous solution of a nickel salt, the nickel ion been present in an amount of not more than one part by weight to about a hundred parts by weight of solution, an alkaline hypophosphite, the hypophosphite radical being present in an amount not substantially in excess of about one part by weight to about a hundred parts by weight of said solution, sodium hydroxyacetate in an amount not substantially in excess of about five parts by weight to about a hundred parts by weight of the solution, and an additive for increasing the rate of deposition of electroless nickel, the additive consisting of seleriic acid in a concentration range of from 0.1 parts to 10 parts per l,000,000 parts of said solution.

To manufacture the file a file bank 3 is covered with a water solluble adhesive. Suitable adhesives are a solution of molasses and water or treacle and water. A mixture of abrasive particles 4 and filler particles 20 is prepared. The abrasive particles 4 are diamond particles and the filler particles 20 are spherical glass beads. The proportion of abrasive particles 4 to filler particles 20 is determined by the coverage of abrasive particles 4 required on the finished file l. The mixture of abrasive particles 4 and filler particles 21. is applied to the file bank 3 by electrostatic attraction. Needless to say the shank l is not covered with adhesive nor with the mix:

When the adhesive has set a number of file blanks 3 are placed in the plating bath l and surrounded by packing particles 21 which are also spherical glass beads. The plating bath is vibrated to ensure that the file blanks 3 are securely held by the packing particles 21 Water is allowed flow through the container until the adhesive is dissolved. The water rinse is then followed by a l0% Hcl solution rinse and a further water rinse. it will be appreciated that although the adhesive has been dissolved the packing particles 21 maintain the abrasive particles 4 and the filler particles 20 in close contact with the file blank 3.

Plating solution is allowed flow by gravity from the supply tank 13 through pipes 11 and the heat exchanger 12 into the plating bath 10. During the plating process the plating solution filters through the filter disc into the lower compartment 18 and then it flows into the drain-off tank 15. The plating solution is returned to the supply tank 13 from the drain-off tank 15 by the pump 14. When sufficient metal is deposited of the file blank 3 the tile blanks 3 are removed from the plating bath 10 and the filler particles removed by dissolving them in hydrofluoric acid. The hydrofluoric acid does not significantly effect the abrasive particles 4 or the nickel deposit.

Subsequently additional nickel may be deposited in another electroless plating bath.

It will be appreciated that tools such as grinding wheels or discs may be manufactured by the same process and several layers of abrasive particles applied.

it will also be appreciated that many other forms of packing particles and filler particles other than glass beads may be used.

A particularly suitable abrasive particle is a diamond particle having a hardness above 9 on the Mohs Scale of hardness.

I claim l. A process of making an abrasive article which includes the following steps in the sequence set forth:

providing a form member to serve as a permanent core for said abrasive article;

selecting a temporary adhesive and a solvent for the temporary adhesive;

placing a layer of the temporary adhesive on the surface of said form;

placing a layer of abrasive particles on the ad-hesive so that the layer of abrasive particles adheres thereto in a dispersed pattern;

packing the form, after thus supplied with adhering abrasive particles, into a body of discreet packing particles which are not soluble in said solvent and are not adhered to said adhesive, said body having interconnecting interstices capable of conducting said solvent;

conducting said solvent into and through said body and to said adhesive until said adhesive is dissolved and removed, said abrasive particles remaining positioned relative to the surface of said form by virtue of the holding power of said packing material; and

thereafter depositing by electroless techniques a metal bond material to the surface of said form thereby trapping solely the abrasive particles in the position they occupied when formerly held by said adhesive.

2. In the process of claim 1, said filler particles being glass and said solvent hydrofluoric acid.

3. A process of making an abrasive article as recited in claim 1 in which a metallic bond is formed by chemical reduction.

4. A process of making an abrasive article as recited in claim 3 in which the metal deposited is a phosphorus nickel alloy containing 5 to 15 percent phosphorus by weight.

5. A process of making an abrasive article as recited in claim 1 in which the adhesive is a water soluble adhesive.

6. A process of making an abrasive article as recited in claim 1 in which the adhesive is dissolved by a water rinse followed by a solution of 5% to 15% hydrochloric acid followed by a further water rinse.

7. A process of making an abrasive article as recited in claim 1 in which the abrasive articles are diamonds having a hardness above 9 on the Mohs Scale of hardness, and the packing particles are glass beads. 

2. In the process of claim 1, said filler particles being glass and said solvent hydrofluoric acid.
 3. A process of making an abrasive article as recited in claim 1 in which a metallic bond is formed by chemical reduction.
 4. A process of making an abrasive article as recited in claim 3 in which the metal deposited is a phosphorus nickel alloy containing 5 to 15 percent phosphorus by weight.
 5. A process of making an abrasive article as recited in claim 1 in which the adhesive is a water soluble adhesive.
 6. A process of making an abrasive article as recited in claim 1 in which the adhesive is dissolved by a water rinse followed by a solution of 5% to 15% hydrochloric acid followed by a further water rinse.
 7. A process of making an abrasive article as recited in claim 1 in which the abrasive articles are diamonds having a hardness above 9 on the Moh''s Scale of hardness, and the packing particles are glass beads. 